Afghan girls in a classroom. Since 2001, the number of girls in schools has risen from a few thousand under the Taliban to 2.7 million. Photograph: Paula Bronstein/Getty Images

The Afghan government has done a deal with the Taliban by which the insurgents will end attacks on state schools in return for a more conservative religious curriculum and the hiring of Taliban-approved mullahs as teachers, according to a report.

The deal, which was agreed at the national level with the Afghan education ministry and at the village level by local communities, appears to have contributed to a fall in the level of violence across much of Afghanistan over the past year. The education ministry even views it as a possible precursor for more comprehensive political negotiations with the Taliban. However, some aid and civil rights groups have raised concerns that such deals could lead to the surrender of hard-won liberties for Afghan children, particularly girls.

The report published by the Afghanistan Analysts Network, a Kabul-based thinktank, said contacts between the Afghan education ministry and the Taliban over schools date back four years, but were discontinued in 2007, allegedly because of US opposition. However, local deals accelerated after the Taliban declared in 2009 that they would end their policy of attacking state schools in return for changes in the curriculum.

According to the report by Antonio Giustozzi and Claudio Franco, the education ministry restarted talks "at the top level to allow for more radical change".

The agreement led to a radical decrease in attacks on schools, with the exceptions being those carried out by non-Taliban insurgents or for other reasons than an opposition to education. In return, schools – including girls' schools – were allowed to reopen in areas under Taliban control or influence on several conditions: that the schools adopt some of the curriculum and textbooks from the Taliban era, which in turn were based on materials used by mujahideen schools during the war against the Soviet army. The Taliban have also insisted on approving the appointment of teachers of religion.

The deal has raised concerns among civil rights and development groups that the gains of the past 10 years could be reversed. Since 2001, the number of children in Afghan schools rose from 1 million to more than 8 million. The number of girls in schools rose from a few thousand under the Taliban to 2.7 million.

Louise Hancock, a policy adviser for Oxfam in Afghanistan, said: "Our concerns would be very much centred on what this means for girls. Will these agreements stop girls going to school? Anecdotal evidence suggests that when armed opposition groups are in control, they are often intimidated into not going by 'night letters' threatening them or their teachers."

Giustozzi and Franco wrote that: "The education ministry leadership seemed keen to turn deal-making on schools into a confidence-building measure for future political negotiations. The Taliban, on the other hand, appear more motivated by the need to improve relations with rural communities, who are themselves increasingly wary of a conflict which never seems to end."